The present invention relates to a device for preventing overflow from a drain.
During rain storms or other extraordinary circumstances a drainage system may become overloaded, and water from higher ground may be forced up out of drains located in lower areas. This is particularly true with drains which are located below grade, as are drains in the basements of buildings. These drains are especially vulnerable because their location below grade may place them on very nearly the same level as a sewer main to which the drain is connected. A small back pressure in the main can cause water to back up through the drain and flood the basement of the building in which it is located, causing damage to the property.
There have been prior devices adapted to seal drains to prevent back flows. Some of these have provided stand pipes which may be rapidly connected to the drain so that back up water will rise in the pipe without flooding the basement. These devices have the disadvantage that if the water level rises above the top of the stand pipe, water then flows into the basement.